connecting these two meshes together
First, join your 2 objects with CtrlJ.
Then you can use the LoopTools &gt; Bridge. First thing, open the Preferences panel and activate the addon called LoopTools, then:

Bevel the inner edge loop, cut a hole:



Select the edges that you want to bridge, right click &gt; LoopTools &gt; Bridge:



Tweak the factors in the Operator box (Segments and Strength):